Preface
The Authors
A1. Reciprocal transformations and their role in the integrability and classification of PDEs
1. Introduction
2. Fundamentals
3. Reciprocal transformations as a way to identify and classify PDEs
4. Reciprocal transformations to derive Lax pairs
5. A Miura-reciprocal transformation
6. Conclusions
A2. Contact Lax pairs and associated (3+l)-dimensional integrable dispersionless systems
1. Introduction
2. Isospectral versus nonisospectral Lax pairs
3. Lax representations for dispersionless systems in (I+I)D and (2+1)D
4. Lax reprcsentations for dispersionless systems in (3+l)D
5. R-matrix approach for dispersionless systems with nonisospectral
Lax representations
A3. Lax pairs for edge-constrained Boussinesq systems of partial difference equations
1. Introduction
2. Gauge equivalence of Lax pairs for PDEs and PAEs
3. Derivation of Lax pairs for Boussinesq systems
4. Gauge and gauge-like equivalences of Lax pairs
5. Application to generalized Hietarinta systems
6. Summary of results
7. Software implementation and conclusions
A4. Lie point symmetries of delay ordinary differential equations
1. Introduction
2. Illustrating example
3. Formulation of the problem for first-order DODEs
4. Construction of invariant first-order DODSs
5. First-order linearDODSs
6. Lie symmetry classification of first-order nonlinear DODSs
7. Exact solutions of the DODSs
8. Higher order DODSs
9. Traffic flow micro-model equation
10. Conclusions
A5. The symmetry approach to integrability: recent advances
1. Introduction
2. The symmetry approach to integrability
3. Integrable non-abelian equations
4. Non-evolutionary systems
A6. Evolution of the concept of h-symmetry and main applications
1. Introduction
2. Basic notions on Lie point symmetries and C∞- symmetries of ODEs
3. Analytical applications of C~-symmetries
4. Extensions and geometric interpretations of C∞-symmetries
A7. Heir-equations for partial differential equations: a 25-year review
1. Introduction
2. Constructing the heir-equations
3. Symmetry solutions of heir-equations
4. Zhdanov's conditional Lie-B~cklund symmetries and heir-equations